U.S. Pat. No. 3,224,927 shows the use of cationic starch to precipitate silica binders onto refractory fibers for forming refractory papers and mats. Although the teachings of this patent are useful for manufacture of shaped ceramic fiber products, the amount of silica binder which can be flocked onto the ceramic fibers is limited by the flocking capacity of the cationic starch; namely, to about 1.5 units silica per unit of starch. In addition, the amount of starch which can be used cannot exceed about 8%. Otherwise, forming times are high and shapes stick to molds. Binder content and formulations therefore are restricted to levels that produce only moderately strong pieces, i.e., 80-120 PSI modulus of rupture. A need therefore exists for improved methods of vacuum forming shaped ceramic fiber products